Poptropica is one example of a game which mostly involves exploring various virtual worlds and solving puzzles; there is a tiny amount of non-gory conflict, but it's a game created by Scholastic Books, so the emphasis is overwhelmingly on education.
I will join the chorus of voices suggesting that you give Minecraft a try in the Creative mode. It allows for some great exploration and has good social potential too. A kid in my son's class set up his own server (able to control who could join it) and a group of the boys from the class built an airport, several other buildings, and a small town. It wasn't without friction and they lost interest (or moved on to other interests) within a year, however it was a great experience.
Roblox has a ton of games (many designed by users of the server). Quite a few involve fighting or shooting down planes/etc, however many do not. The setting might be a pizza parlor or other business where the players take on certain roles such as making the pizza in the virtual world, serve customers, drive to a location to deliver them, etc. Or they can build their own house and furnish it, get room-mates, go to work, etc. My 13-year old loves the games where they simulate flying planes. So there are a good number of options there, though you need to monitor game selection. The server does screen language, as I recall, and the kids are told to report anyone asking for personal information.
I personally am really fine with the kids interacting with other players in the online environment. It can supplement their face-to-face friendships and it provides a low-risk place for learning about social interactions. Sometimes another player behaves like a jerk or my kid indulges in less-kind behavior, and the kid can learn about the consequences of those actions in a way which doesn't affect their 'real life' status.
Anyway, good luck with it!